This account is pending registration confirmation. Please click on the link within the confirmation email previously sent you to complete registration.Need a new registration confirmation email? Click here

My take: I don't believe that U.S. equities overall are in a bubble. Though stocks certainly are no longer cheap, valuations are still a long way off from the late 1990s or the run-up to the 1987 stock market crash. That said, valuations certainly have started to become an issue, particularly for certain segments of the market.

For instance, at more than 25x current earnings estimates, valuations for small caps look outright expensive. And particular pockets of the market - like last year's growth stocks-are verging, or have already tipped into, bubble territory. The average price-to-book ratio for the Nasdaq Biotechnology Index is more than 7. As for Internet stocks, we are back to a world reminiscent of the late 1990s, where only the most creative metrics can justify the premiums being paid for certain companies.

Does all this suggest that the market has peaked and stocks are likely to come crashing down? Not necessarily. It's important to note that not all stocks look expensive. In the United States, the energy, healthcare, and surprisingly technology (not every tech stock is trading like Facebook) sectors are all trading comfortably below their historic valuations. Outside of the United States, stocks in Europe, Japan, and most of developed Asia range from reasonably priced to cheap.

In addition, while the market is certainly vulnerable to a spike in interest rates or an economy slowing more than expected, I don't expect these scenarios to occur. Rather, given my expectations of modestly accelerating economic growth and continued low rates in 2014, I still believe that the U.S. market will push ahead this year.